Climatologist Inez Fung looks at Earth's atmosphere to get answers about the climate on our planet. When you gaze up at the sky, it appears to have no boundaries. But Earth does have limits—it is a closed system—and Earth's atmosphere prevents many things (except sunlight) from entering or leaving the system.  Water, carbon dioxide, and nitrogen circulate within the system in processes called cycles. Inez studies all these cycles to predict what may happen to Earth's climate in the future. She uses computer models to simulate the many variables that affect climate.

In this activity you'll make your own closed system—a mini-greenhouse in a bottle. You will observe your greenhouse and look for evidence of any of the cycles found on Earth. If you set it up correctly and give it the right amount of sunlight and water, your greenhouse will thrive without any help from you.

1. Print this activity. Print this page and your Life in a Bottle Journal. 2. Clean the bottle. Rinse your empty 2-liter bottle and peel off the label. 3. Measure and cut the bottle. Measure 5 inches from the bottom of the bottle and make a mark. Repeat four times to make five marks around the bottle. Then connect all the marks to create a cutting line around the entire bottle and cut the bottle along the line carefully with scissors.

Fill the bottom section of the bottle with a one-and-a-half inch layer of rocks or gravel. Place soil on top of the rocks until the bottom section is halfway filled.

Plant seeds according to the instructions on the package.

Water your seeds with approximately one-half cup of water.

Place the top of the bottle back on (with the cap in place) and tape it shut.

Put your bottle in direct sunlight.

Check your greenhouse every day. If there are always many water droplets on the inside of the bottle, if mold or mildew forms, or if water runs down the sides of the bottle, you need to take the top off of your greenhouse for the night. If no water droplets are forming, your greenhouse needs just a little more water.

[ Write your observations in the Life in a Bottle Journal—the amount of water droplets that form in the bottle, how much water collects at the bottom of the bottle, when your seeds start to sprout, and how much the seeds grow each day. Observe for at least two weeks after the seeds have sprouted, and then keep observing your greenhouse for as long as you like.

When a scientist finishes an experiment, she always writes up her notes and analyzes her data. Write your analysis here, starting with a few simple questions.